I'm getting the folder with a?

I too have this issue on a mid 2012 unibody MBP.

It was running a Samsung SSD, flawlessly for years (purchased 2016), then it crashed one day last week and wouldn’t start. I got the folder with a ? in it and went through an internet recovery, whereupon, after downloading the OS, the machine restarted to the prohibitory symbol.

I installed a brand new Samsung SSD, formatted it to journaled in disk utility and then downloaded the OS again, assuming the 8 year old previous SSD (which I had used in previous iterations of MBP) had developed a fault. Same thing happened - it restarted to the prohibitory symbol.

Perhaps tellingly, the original SSD, when placed in a caddy enabled the Mac to start up as normal through a USB cable.

I therefore suspect the issue is a SATA cable failure, as you imply can be a cause.

What’s your view based on this description?

thanks.

Damian.